Aortic dissection: Clinical sciences

Aortic dissection occurs often due to long-standing untreated high blood pressure, when blood tears through the intimal layer of the aortic wall and bleeds into the muscular layer, creating an intraluminal flap and a double lumen, which means that there is a true and a false lumen of the aorta.

Acutely, blood will flow into the false lumen because there’s less resistance, which can lead to obstruction of the true lumen, resulting in malperfusion of end-organs, such as the brain, bowel, or kidneys. In addition, as blood accumulates in the false lumen with no way out, it may clot leading to the formation of thrombi.

Lastly, as blood keeps flowing into the false lumen, the shear stress on the aortic wall can cause the tear to expand, or in the worst cases even lead to aortic rupture, causing mortality from cardiac tamponade or internal hemorrhage.

According to the Stanford classification, aortic dissection is either classified as Type A, which always involves the ascending aorta with or without involving the descending aorta; and Type B, which only involves the descending aorta.

Let’s first look at an unstable case. When approaching a patient who presents with signs and symptoms suggestive of an acute aortic dissection, your first step is to do an ABCDE assessment in order to determine if the patient is unstable or stable. If the patient is unstable, you need to stabilize their airway, breathing, and circulation first. This means that you should secure their airway, obtain IV access, and begin fluid resuscitation while continuously monitoring their vital signs, especially their blood pressure and heart rate.

Next, take a focused history and physical exam. Patients with unstable aortic dissections typically report an acute and severe “tearing” or “ripping” chest pain, and since the aorta is mostly a retroperitoneal organ, the pain can radiate to the back. In fact, the location of the pain depends on which area of the aorta is affected, and sometimes the pain can evolve and migrate as the dissection expands.